1. Field
The present disclosure is directed to a method and apparatus for transmit power calibration in a wireless system, and more particularly to modifying transmit power settings based on a desired power level.
2. Introduction
Presently, efforts are underway to standardize uplink power control for Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), also referred to as Evolved Universal Terrestrial Radio Access (EUTRA). While exact implementation details are yet to be finalized, it is generally understood that terminals, such as user equipment (UE), in a EUTRA network will have to transmit at at distinct power levels that are determined by a specific power control formula. It is also generally understood that, for each terminal, the power control formula attempts to maintain per subcarrier power, such as the power spectral density (PSD) of the signal received at the base station, at a desired level. If the received PSD has to be kept at a particular level, and the number of subcarriers allocated to a UE is significantly different in each subframe, then total transmit power of each EUTRA UE will change considerably from subframe to subframe. Maintaining transmit power accuracy, with rapidly changing transmission bandwidth and frequency, such as would occur where a separate sets of subcarriers may be allocated to a UE in different subframes, will be a significant challenge for UE hardware implementation. Without any mitigation mechanisms in place, UEs in the EUTRA network will make significant errors in the transmit power which will result in a considerable loss in spectral efficiency.
Thus, there is a need for a method and apparatus for transmit power calibration in a frequency division multiplexed wireless system.